Answer: m = 0
Step-by-step explanation:
Complete question :
The 100m dah times in the girl's track meet were normally distributed with a mean of 13 seconds and a standard deviation of 0.3 seconds.
Lana finished the race in 13.2 seconds . If 84 other girls ran in the event, approximately how many runners did she beat?
Answer:
21 runners
Step-by-step explanation:
Mean, μ = 13 seconds
Standard deviation, σ = 0.3
Lana's race time = 13.2
We find the proportion of runners who had race time above 13.2 ;
Proportion of who had race tune above 13.2
P(x > 13.2)
Obtain the Zscore
Zscore = (x - μ) / σ
Z = (13.2 - 13) / 0.3
Zscore = 0.2 / 0.3 = 0.6667
P(Z > 0.6667) = 0.25239 (Z probability calculator)
This is about 0.25239 * 100 = 25.24% = 25% (nearest percent)
Hence, Number of runners Lana beat = 25% of total runners ;
0.25 * 84 = 21
Hence, Lana beat about 21 runners
Answer:
she bought 5 erasers
Step-by-step explanation:
25-5 is 20 and 20 divided by 4 is 5
Answer: three pieces.
The piece of wood is 6/8 inches long - this fraction can be simplified to 3/4 by dividing both the numerator and denominator by 2.
Thus, he cuts a piece of wood that is 3/4 inches long into 1/4 inch pieces.
1 goes into 3 three times, so the piece of wood can be cut into three 1/4-inch pieces.
Answer:
We have 197 g of Co-60 after 18 months.
Step-by-step explanation:
We can use the decay equation.
Where:
- M(f) and M(i) are the final and initial mass respectively
- λ is the decay constant (ln(2)/t(1/2))
- t(1/2) is the half-life of Co
- t is the time at the final amount of m
<u>Therefore, we have 197 g of Co-60 after 18 months.</u>
I hope it helps you!
